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Diffraction at the Tevatron: CDF Results

Diffraction at the Tevatron: CDF Results. K. Goulianos The Rockefeller University.  presented on behalf of the CDF Collaboration . Diffraction 2006 Milos island, Greece, 5-10 September 2006. Contents. Run-I diffraction @ CDF Run II results Diffractive structure function

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Diffraction at the Tevatron: CDF Results

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  1. Diffraction at the Tevatron: CDF Results K. Goulianos The Rockefeller University  presented on behalf of the CDF Collaboration Diffraction 2006Milos island, Greece, 5-10 September 2006

  2. Contents • Run-I diffraction @ CDF • Run II results • Diffractive structure function  xBj, Q2, and t dependence • Exclusive production  dijet & diphoton Diffraction at the Tevatron: CDF resultsK. Goulianos

  3. Run-I Diffraction @ CDF sT=Im fel (t=0) Elastic scattering Total cross section f f OPTICAL THEOREM GAP h h DD DPE SDD=SD+DD SD Diffraction at the Tevatron: CDF resultsK. Goulianos

  4. Run I-0 (1988-89) Elastic, single diffractive, and total cross sections @ 546 and 1800 GeV Roman Pot Spectrometers • Roman Pot Detectors • Scintillation trigger counters • Wire chamber • Double-sided silicon strip detector Additional Detectors Trackers up to |h| = 7 • Results • Total cross section stot ~ se • Elastic cross section ds/dt ~ exp[2a’ lns]  shrinking forward peak • Single diffraction Breakdown of Regge factorization Diffraction at the Tevatron: CDF resultsK. Goulianos

  5. Breakdown of Regge factorization Factorization  Pomeron flux KG, PLB 358 (1995) 379 Diffraction at the Tevatron: CDF resultsK. Goulianos

  6. Run-IC beam Run-IA,B,C Run-IA,B Forward Detectors BBC 3.2<h<5.9 FCAL 2.4<h<4.2 Diffraction at the Tevatron: CDF resultsK. Goulianos

  7. Central and Double Gaps @ CDF • Double Diffraction Dissociation • One central gap • Double Pomeron Exchange • Two forward gaps • SDD: Single+Double Diffraction • One forward + one central gap Results: DD, like SD, is suppressed The formation of the second gap in two-gap events is not suppressed! Diffraction at the Tevatron: CDF resultsK. Goulianos

  8. dN/dh % Fraction (+/-) W 1.15 (0.55) JJ 0.75 (0.10) h b 0.62 (0.25) J/y 1.45 (0.25) Hard Diffractive Fractions @ CDF Fraction: SD/ND ratio at 1800 GeV All ratios ~ 1% ~ uniform suppression ~ FACTORIZATION ! Diffraction at the Tevatron: CDF resultsK. Goulianos

  9. Diffractive Structure Function:Breakdown of QCD Factorization b = momentum fraction of parton in Pomeron The diffractive structure function at the Tevatron is suppressed by a factor of ~10 relative to expectation from pdf’s measured by H1 at HERA Similar suppression factor as in soft diffraction relative to Regge expectations! H1 CDF Using preliminary pdf’s from Diffraction at the Tevatron: CDF resultsK. Goulianos

  10. R(SD/ND) R(DPE/SD) DSF from two/one gap: factorization restored! Restoring factorization:multigap diffraction w/preliminary pdf’s from The diffractive structure function measured on the proton side in events with a leading antiproton is NOT suppressed relative to predictions based on DDIS Diffraction at the Tevatron: CDF resultsK. Goulianos

  11. Run II Results • Diffractive structure function NEW: • Q2 - dependence • t - dependence • Exclusive production • dijet • diphoton Diffraction at the Tevatron: CDF resultsK. Goulianos

  12. ROMAN POT DETECTORS BEAM SHOWER COUNTERS: Used to reject ND events MINIPLUG CALORIMETER CDF in Run-II Diffraction at the Tevatron: CDF resultsK. Goulianos

  13. The MiniPlugs @ CDF Diffraction at the Tevatron: CDF resultsK. Goulianos

  14. DIFFRACTIVE STRUCTURE FUNCTION Systematic uncertainties due to energy scale and resolution cancel out in the ratio Diffraction at the Tevatron: CDF resultsK. Goulianos

  15. Diffractive Dijet Signal • - Bulk of data taken with RPS trigger but no RPS tracking • Extract x from calorimetric information • Calibrate calorimetric x using limited sample of RPS tracking data • Subtract overlap background using a rescaled dijet event sample • Verify diffractive x range by comparing xRPS with xCAL Overlap events: mainly ND dijets plus SD low x RPS trigger Diffraction at the Tevatron: CDF resultsK. Goulianos

  16. Alignment of RPS using Data maximize the |t|-slope  determine X and Y offsets Diffraction at the Tevatron: CDF resultsK. Goulianos

  17. xCAL Calibration overlap events signal region xcal distributionfor slice of xRPS / mean ~ 30% Diffraction at the Tevatron: CDF resultsK. Goulianos

  18. jet p jet p Dijet Properties SD boosted opposite to pbar Diffraction at the Tevatron: CDF resultsK. Goulianos

  19. 120 GeV ET distributions Diffraction at the Tevatron: CDF resultsK. Goulianos

  20. Diffractive Structure Function:Q2 dependence ETjet ~ 100 GeV ! • Small Q2 dependence in region 100 < Q2 < 10,000 GeV2 • Pomeron evolves as the proton! Diffraction at the Tevatron: CDF resultsK. Goulianos

  21. Diffractive Structure Function:t- dependence Fit ds/dt to a double exponential: • Same slope over entire region of 0 < Q2 < 4,500 GeV2 across soft and hard diffraction! • No diffraction dips • No Q2 dependence in slope from inclusive to Q2~104 GeV2 Diffraction at the Tevatron: CDF resultsK. Goulianos

  22. Diffractive dijets: Df=fpbar-fdijet Diffraction at the Tevatron: CDF resultsK. Goulianos

  23. H EXCLUSIVE PRODUCTION Measure exclusive jj & gg  Calibrate predictions for H production rates @ LHC Bialas, Landshoff, Phys.Lett. B 256,540 (1991) Khoze, Martin, Ryskin, Eur. Phys. J. C23, 311 (2002); C25,391 (2002);C26,229 (2002) C. Royon, hep-ph/0308283 B. Cox, A. Pilkington, PRD 72, 094024 (2005) OTHER………………………… KMR: sH(LHC) ~ 3 fb S/B ~ 1 if DM ~ 1 GeV Clean discovery channel Search for exclusive gg Search for events with two high ET gammas and no other activity in the calorimeters or BSCs Search for exclusive dijets: Measure dijet mass fraction Look for signal as Mjj 1 Diffraction at the Tevatron: CDF resultsK. Goulianos

  24. Exclusive Dijet Signal Dijet fraction – all jets b-tagged dijet fraction DIJETS Exclusive b-jets are suppressed by JZ= 0 selection rule Excess over MC predictions at large dijet mass fraction Diffraction at the Tevatron: CDF resultsK. Goulianos

  25. RJJ(excl): Data vs MC Exclusive DPE (DPEMC)  non-pQCD based on Regge theory ExHuME (KMR): gggg process  uses LO pQCD Shape of excess of events at high Rjj is well described by both models Diffraction at the Tevatron: CDF resultsK. Goulianos

  26. jjexcl: Exclusive Dijet Signal COMPARISON Inclusive data vs MC @ b/c-jet data vs inclusive Diffraction at the Tevatron: CDF resultsK. Goulianos

  27. JJexcl : x-section vs ET(min) Comparison with hadron level predictions ExHuME (red) Exclusive DPE in DPEMC (blue) Diffraction at the Tevatron: CDF resultsK. Goulianos

  28. JJexcl : cross section predictions ExHuME Hadron-Level Differential Exclusive Dijet Cross Section vs Dijet Mass (dotted/red):Default ExHuME prediction (points): Derived from CDF Run II Preliminary excl. dijet cross sections Statistical and systematic errors are propagated from measured cross section uncertainties using ExHuME Mjj distribution shapes. Diffraction at the Tevatron: CDF resultsK. Goulianos

  29. JJexcl: R(excl/incl) vs ETmin Diffraction at the Tevatron: CDF resultsK. Goulianos

  30. Exclusive gg/ee Search QED process: cross-check to exclusive gg • (anti)proton not detected • require 2 EM showers (ET>5 GeV, |h|<2) • veto on all BSCs and cal towers except for those of the 2 EM showers • L~530 pb-1 delivered  Leffective=46 pb-1 •  19 events with 2 EM showers + ”nothing” [above threshold] Diffraction at the Tevatron: CDF resultsK. Goulianos

  31. Exclusive ee Search control sample for gg search ET1=6.1 GeV ET2=6.0 GeV 16 candidate events found background: good agreement with LPAIR: Diffraction at the Tevatron: CDF resultsK. Goulianos

  32. Exclusive ggSearch ET1=6.8 GeV/c ET2=5.9 GeV/c Diffraction at the Tevatron: CDF resultsK. Goulianos

  33. Summary Run I • Suppression of single gap diffraction • M2 – scaling: ds/dM2 independent of s • Non-suppressed double-gap to single-gap ratios Run II • Diffractive structure function vs xBj, Q2, and t Composite Pomeron made up from proton pdf’s ? • Exclusive production; dijet and diphoton  Diffractive Higgs @ LHC under control Diffraction at the Tevatron: CDF resultsK. Goulianos

  34. BACKUP Diffraction at the Tevatron: CDF resultsK. Goulianos

  35. POMERON p-p Interactions Non-diffractive: Color-exchange Diffractive: Colorless exchange w/vacuum quantum numbers rapidity gap Incident hadrons acquire color and break apart Incident hadrons retain their quantum numbers remaining colorless Goal: understand the QCD nature of the diffractive exchange Diffraction at the Tevatron: CDF resultsK. Goulianos

  36. renormalization 1 M2 - scaling KG&JM, PRD 59 (1999) 114017  Independent of S over a range of six orders of magnitude in M2 ! Factorization breaks down so as to ensure M2-scaling! Diffraction at the Tevatron: CDF resultsK. Goulianos

  37. Pomeron dominated x-dependence: Inclusive vs Dijet Diffraction at the Tevatron: CDF resultsK. Goulianos

  38. The MiniPlug Calorimeters About 1500 wavelength shifting fibers of 1 mm dia. are ‘strung’ through holes drilled in 36x¼” lead plates sandwiched between reflective Al sheets and guided into bunches to be viewed individually by multi-channel photomultipliers. Diffraction at the Tevatron: CDF resultsK. Goulianos

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